It is Thursday night in Dagenham & Barking, the East London stronghold of the far-right British National Party, and half a dozen activists are pushing petitions against knife crime through the letter boxes of a nondescript housing estate.

They are cheery, plain-spoken East Enders who could not care less that their names, jobs and addresses were published on the internet – along with the rest of the BNP’s 12,000 members – this week. Or that their families have since received abusive and threatening telephone calls.

“It shows we’re ordinary people . . . We’re a legitimate party,” says Mike Wood, 62, a former soldier.

They are people who have seen their neighbourhoods changed by mass immigration, feel that the mainstream parties have failed to address their concerns, and – rightly or wrongly – have thrown in their lot with a BNP that claims to have renounced its brutish, racist past.

If there is a public face of what might be called new BNP it is surely Richard Barnbrook – the man who represents this ward and is organising the leafleting. He is leader of the opposition on Barking & Dagenham council, the recipient of 130,000 votes in last May’s elections to the London Assembly and the most senior elected official his party has ever had.

On this night – between calls on a mobile phone whose ring tone is Jerusalem– Mr Barnbrook, 47, is the very model of moderation. The leafleting over, he takes me to the cul-de-sac where he lives, points to each house, and tells me the origin of each occupant – English, Asian, Caribbean, East European. There is no violence, no late-night rows, no antisocial behaviour, he says. “It’s a diversity that works really well” – an extraordinary statement from a senior member of a party that abhors multiculturalism.

Mr Barnbrook’s house is the one with the large Union Jack and Cross of St George hanging from two flag-poles on the front.

Inside, a cartoon British bulldog is stuck in the living-room mirror, a Union Jack paperweight beneath the television. It looks like the bachelor pad that it is, though Simon Darby, the BNP’s spokesman and Mr Barnbrook’s assistant in the London Assembly, sometimes stays during the week. I ask about Simone Clarke, the former lead ballerina with the English National Ballet and BNP sympathiser to whom – in the campaign for the assembly elections – Mr Barnbrook was very publicly engaged. No longer, he says. “We’ve separated . . . It probably wasn’t meant to be.”

Mr Barnbrook is not like his fellow leafleters. He trained as an artist at the Royal Academy, collaborated for a while with the gay film-maker Derek Jarman, and once made a homoerotic film before joining the notoriously homophobic BNP. And as we talk, it becomes clear that he also inhabits a very different world.

Mr Barnbrook suggests, without a trace of irony, that the BNP will have 60 MPs within six years – and that the Government and its intelligence service stooges are out to destroy it before that happens. Indeed, he even says that the party might have been the victim of “state infiltration”.

He deplores the membership list leak, but says that it has done the party good. Donations have poured in. Its website has received so many hits it has crashed twice. The perpetrators have scored an own goal “totally, absolutely and without a shadow of a doubt”, he says with a boyish grin.

Mr Barnbrook has no doubt that the BNP will soon become a real electoral threat to the Establishment. This will happen, he says, as the economy collapses and Britain begins to experience widespread social unrest and riots. “The mainstream parties have viewed the upper working class and the middle class as being the core element of their vote, but once their aspirations have been destroyed they will say, ‘We can no longer trust these parties. Who can we turn to?’ ” He predicts that the BNP will win up to four seats at the next general election – he names Stoke, Dagenham and Barking, where he will stand, as three targets. But that will be just the start. “In 2013 or 2014 we should have up to 10 per cent of Parliament.”

It is time for a reality check. The BNP’s biggest achievement to date is a lone seat on the London Assembly, and in the six months since his election Mr Barnbrook has hardly started a revolution. Only five of the twenty-four other members talk to him. This week he walked out of a committee meeting after being called a Nazi. “Does it bother me? Not at all. My skin is far thicker than they can ever perceive.”

I put that to the test. I ask him about a charge levelled by his many foes – that he likes his drink.

Mr Barnbrook indignantly denies it. He used to have three or four pints a night, he admits, but claims that in the past six months he has virtually stopped. “They can’t find any thuggery in me, or robbery, so they try to find something to niggle at . . . If they can’t get me on the drinking aspect they say I’m a gay Marxist porno star. Then they say I’m a gigolo. Make their mind up. What am I? If that’s the best they can offer bring it on!”

The interview over, Mr Barnbrook walks to the station with me to buy a paper. When we part he enters a convenience store. I linger to make a call and spot him leaving the shop empty-handed. He goes round the corner. A few minutes later I see him walking home. Around the corner I find an off-licence, and the staff tell me that Mr Barnbrook bought four large bottles of cider and Guinness.

Later I call Mr Barnbrook. He insists that the drink was for visitors. I have no reason to doubt him, but the vignette hints at the much wider problem with today’s sanitised, repackaged BNP leadership and its claims to respectability: what can you believe?

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